Polyaniline Nanorings and Flat Hollow Capsules Synthesized by <i>in Situ</i> Sacrificial Oxidative Templates

Abstract

An in situ sacrificial oxidative template route has been developed for the bulk synthesis of two-dimensional polyaniline nanostructures, such as nanorings and flat hollow capsules. In the reaction system, VOPO 4 ·2H 2 O nanoplates formed spontaneously in V 2 O 5 /H 2 O 2 /H 3 PO 4 mixture can serve as both oxidant and sacrificial template for the chemical oxidative polymerization of aniline. The synthetic parameters, such as reaction times, the concentrations of H 3 PO 4, and types of the oxidants on the morphologies, sizes, and molecular structures of polyaniline nanostructures have been investigated. The time-dependent experiments reveal that VOPO 4 ·2H 2 O nanoplate is etched gradually with the polymerization reaction proceeding. The concentration of H 3 PO 4 can adjust the polymerization rate of aniline as well as the etching rate of VOPO 4 ·2H 2 O, which is critical for controlled synthesis of polyaniline nanorings and flat hollow capsules. The sacrificial oxidative template approach can be extended to synthesize two-dimensional polypyrrole nanostructures.